- 11 6月, 2014 1 次提交
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由 Octavian Purdila 提交于
tcp_fragment can be called from process context (from tso_fragment). Add a new gfp parameter to allow it to preserve atomic memory if possible. Signed-off-by: NOctavian Purdila <octavian.purdila@intel.com> Reviewed-by: NChristoph Paasch <christoph.paasch@uclouvain.be> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 23 5月, 2014 1 次提交
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由 Neal Cardwell 提交于
Experience with the recent e114a710 ("tcp: fix cwnd limited checking to improve congestion control") has shown that there are common cases where that commit can cause cwnd to be much larger than necessary. This leads to TSO autosizing cooking skbs that are too large, among other things. The main problems seemed to be: (1) That commit attempted to predict the future behavior of the connection by looking at the write queue (if TSO or TSQ limit sending). That prediction sometimes overestimated future outstanding packets. (2) That commit always allowed cwnd to grow to twice the number of outstanding packets (even in congestion avoidance, where this is not needed). This commit improves both of these, by: (1) Switching to a measurement-based approach where we explicitly track the largest number of packets in flight during the past window ("max_packets_out"), and remember whether we were cwnd-limited at the moment we finished sending that flight. (2) Only allowing cwnd to grow to twice the number of outstanding packets ("max_packets_out") in slow start. In congestion avoidance mode we now only allow cwnd to grow if it was fully utilized. Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 14 5月, 2014 2 次提交
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由 Yuchung Cheng 提交于
To avoid large code duplication in IPv6, we need to first simplify the complicate SYN-ACK sending code in tcp_v4_conn_request(). To use tcp_v4(6)_send_synack() to send all SYN-ACKs, we need to initialize the mini socket's receive window before trying to create the child socket and/or building the SYN-ACK packet. So we move that initialization from tcp_make_synack() to tcp_v4_conn_request() as a new function tcp_openreq_init_req_rwin(). After this refactoring the SYN-ACK sending code is simpler and easier to implement Fast Open for IPv6. Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDaniel Lee <longinus00@gmail.com> Signed-off-by: NJerry Chu <hkchu@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Yuchung Cheng 提交于
Consolidate various cookie checking and generation code to simplify the fast open processing. The main goal is to reduce code duplication in tcp_v4_conn_request() for IPv6 support. Removes two experimental sysctl flags TFO_SERVER_ALWAYS and TFO_SERVER_COOKIE_NOT_CHKD used primarily for developmental debugging purposes. Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDaniel Lee <longinus00@gmail.com> Signed-off-by: NJerry Chu <hkchu@google.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 04 5月, 2014 1 次提交
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由 Eric Dumazet 提交于
Commit e114a710 ("tcp: fix cwnd limited checking to improve congestion control") obsoleted in_flight parameter from tcp_is_cwnd_limited() and its callers. This patch does the removal as promised. Signed-off-by: NEric Dumazet <edumazet@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 03 5月, 2014 1 次提交
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由 Eric Dumazet 提交于
Yuchung discovered tcp_is_cwnd_limited() was returning false in slow start phase even if the application filled the socket write queue. All congestion modules take into account tcp_is_cwnd_limited() before increasing cwnd, so this behavior limits slow start from probing the bandwidth at full speed. The problem is that even if write queue is full (aka we are _not_ application limited), cwnd can be under utilized if TSO should auto defer or TCP Small queues decided to hold packets. So the in_flight can be kept to smaller value, and we can get to the point tcp_is_cwnd_limited() returns false. With TCP Small Queues and FQ/pacing, this issue is more visible. We fix this by having tcp_cwnd_validate(), which is supposed to track such things, take into account unsent_segs, the number of segs that we are not sending at the moment due to TSO or TSQ, but intend to send real soon. Then when we are cwnd-limited, remember this fact while we are processing the window of ACKs that comes back. For example, suppose we have a brand new connection with cwnd=10; we are in slow start, and we send a flight of 9 packets. By the time we have received ACKs for all 9 packets we want our cwnd to be 18. We implement this by setting tp->lsnd_pending to 9, and considering ourselves to be cwnd-limited while cwnd is less than twice tp->lsnd_pending (2*9 -> 18). This makes tcp_is_cwnd_limited() more understandable, by removing the GSO/TSO kludge, that tried to work around the issue. Note the in_flight parameter can be removed in a followup cleanup patch. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 01 5月, 2014 1 次提交
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由 Eric Dumazet 提交于
Both TLP and Fast Open call __tcp_retransmit_skb() instead of tcp_retransmit_skb() to avoid changing tp->retrans_out. This has the side effect of missing SNMP counters increments as well as tcp_info tcpi_total_retrans updates. Fix this by moving the stats increments of into __tcp_retransmit_skb() Signed-off-by: NEric Dumazet <edumazet@google.com> Acked-by: NNandita Dukkipati <nanditad@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 23 4月, 2014 1 次提交
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由 Eric Dumazet 提交于
In commit 0e280af0 ("tcp: introduce TCPSpuriousRtxHostQueues SNMP counter") we added a logic to detect when a packet was retransmitted while the prior clone was still in a qdisc or driver queue. We are now confident we can do better, and catch the problem before we fragment a TSO packet before retransmit, or in TLP path. This patch fully exploits the logic by simply canceling the spurious retransmit. Original packet is in a queue and will eventually leave the host. This helps to avoid network collapses when some events make the RTO estimations very wrong, particularly when dealing with huge number of sockets with synchronized blast. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 21 4月, 2014 1 次提交
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由 Weiping Pan 提交于
Make tcp_cwnd_application_limited() static and move it from tcp_input.c to tcp_output.c Signed-off-by: NWeiping Pan <wpan@redhat.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 16 4月, 2014 1 次提交
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由 Eric Dumazet 提交于
ip_queue_xmit() assumes the skb it has to transmit is attached to an inet socket. Commit 31c70d59 ("l2tp: keep original skb ownership") changed l2tp to not change skb ownership and thus broke this assumption. One fix is to add a new 'struct sock *sk' parameter to ip_queue_xmit(), so that we do not assume skb->sk points to the socket used by l2tp tunnel. Fixes: 31c70d59 ("l2tp: keep original skb ownership") Reported-by: NZhan Jianyu <nasa4836@gmail.com> Tested-by: NZhan Jianyu <nasa4836@gmail.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 28 3月, 2014 1 次提交
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由 Eric Dumazet 提交于
There is no need to allocate 15 bytes in excess for a SYNACK packet, as it contains no data, only headers. SYNACK are always generated in softirq context, and contain a single segment, we can use TCP_INC_STATS_BH() Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 27 3月, 2014 1 次提交
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由 Peter Pan(潘卫平) 提交于
After commit d4589926 (tcp: refine TSO splits), tcp_nagle_check() does not use parameter mss_now anymore. Signed-off-by: NWeiping Pan <panweiping3@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 12 3月, 2014 1 次提交
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由 Eric Dumazet 提交于
Lars Persson reported following deadlock : -000 |M:0x0:0x802B6AF8(asm) <-- arch_spin_lock -001 |tcp_v4_rcv(skb = 0x8BD527A0) <-- sk = 0x8BE6B2A0 -002 |ip_local_deliver_finish(skb = 0x8BD527A0) -003 |__netif_receive_skb_core(skb = 0x8BD527A0, ?) -004 |netif_receive_skb(skb = 0x8BD527A0) -005 |elk_poll(napi = 0x8C770500, budget = 64) -006 |net_rx_action(?) -007 |__do_softirq() -008 |do_softirq() -009 |local_bh_enable() -010 |tcp_rcv_established(sk = 0x8BE6B2A0, skb = 0x87D3A9E0, th = 0x814EBE14, ?) -011 |tcp_v4_do_rcv(sk = 0x8BE6B2A0, skb = 0x87D3A9E0) -012 |tcp_delack_timer_handler(sk = 0x8BE6B2A0) -013 |tcp_release_cb(sk = 0x8BE6B2A0) -014 |release_sock(sk = 0x8BE6B2A0) -015 |tcp_sendmsg(?, sk = 0x8BE6B2A0, ?, ?) -016 |sock_sendmsg(sock = 0x8518C4C0, msg = 0x87D8DAA8, size = 4096) -017 |kernel_sendmsg(?, ?, ?, ?, size = 4096) -018 |smb_send_kvec() -019 |smb_send_rqst(server = 0x87C4D400, rqst = 0x87D8DBA0) -020 |cifs_call_async() -021 |cifs_async_writev(wdata = 0x87FD6580) -022 |cifs_writepages(mapping = 0x852096E4, wbc = 0x87D8DC88) -023 |__writeback_single_inode(inode = 0x852095D0, wbc = 0x87D8DC88) -024 |writeback_sb_inodes(sb = 0x87D6D800, wb = 0x87E4A9C0, work = 0x87D8DD88) -025 |__writeback_inodes_wb(wb = 0x87E4A9C0, work = 0x87D8DD88) -026 |wb_writeback(wb = 0x87E4A9C0, work = 0x87D8DD88) -027 |wb_do_writeback(wb = 0x87E4A9C0, force_wait = 0) -028 |bdi_writeback_workfn(work = 0x87E4A9CC) -029 |process_one_work(worker = 0x8B045880, work = 0x87E4A9CC) -030 |worker_thread(__worker = 0x8B045880) -031 |kthread(_create = 0x87CADD90) -032 |ret_from_kernel_thread(asm) Bug occurs because __tcp_checksum_complete_user() enables BH, assuming it is running from softirq context. Lars trace involved a NIC without RX checksum support but other points are problematic as well, like the prequeue stuff. Problem is triggered by a timer, that found socket being owned by user. tcp_release_cb() should call tcp_write_timer_handler() or tcp_delack_timer_handler() in the appropriate context : BH disabled and socket lock held, but 'owned' field cleared, as if they were running from timer handlers. Fixes: 6f458dfb ("tcp: improve latencies of timer triggered events") Reported-by: NLars Persson <lars.persson@axis.com> Tested-by: NLars Persson <lars.persson@axis.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 11 3月, 2014 1 次提交
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由 Eric Dumazet 提交于
All skb in socket write queue should be properly timestamped. In case of FastOpen, we special case the SYN+DATA 'message' as we queue in socket wrote queue the two fallback skbs: 1) SYN message by itself. 2) DATA segment by itself. We should make sure these skbs have proper timestamps. Add a WARN_ON_ONCE() to eventually catch future violations. Fixes: 740b0f18 ("tcp: switch rtt estimations to usec resolution") Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Acked-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 08 3月, 2014 1 次提交
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由 Eric Dumazet 提交于
Usage of skb->tstamp should remain private to TCP stack (only set on packets on write queue, not on cloned ones) Otherwise, packets given to loopback interface with a non null tstamp can confuse netif_rx() / net_timestamp_check() Other possibility would be to clear tstamp in loopback_xmit(), as done in skb_scrub_packet() Fixes: 740b0f18 ("tcp: switch rtt estimations to usec resolution") Signed-off-by: NEric Dumazet <edumazet@google.com> Reported-by: NWillem de Bruijn <willemb@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 07 3月, 2014 1 次提交
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由 David S. Miller 提交于
Can be invoked from non-BH context. Based upon a patch by Eric Dumazet. Fixes: f19c29e3 ("tcp: snmp stats for Fast Open, SYN rtx, and data pkts") Reported-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 04 3月, 2014 2 次提交
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由 Yuchung Cheng 提交于
Add the following snmp stats: TCPFastOpenActiveFail: Fast Open attempts (SYN/data) failed beacuse the remote does not accept it or the attempts timed out. TCPSynRetrans: number of SYN and SYN/ACK retransmits to break down retransmissions into SYN, fast-retransmits, timeout retransmits, etc. TCPOrigDataSent: number of outgoing packets with original data (excluding retransmission but including data-in-SYN). This counter is different from TcpOutSegs because TcpOutSegs also tracks pure ACKs. TCPOrigDataSent is more useful to track the TCP retransmission rate. Change TCPFastOpenActive to track only successful Fast Opens to be symmetric to TCPFastOpenPassive. Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NNandita Dukkipati <nanditad@google.com> Signed-off-by: NLawrence Brakmo <brakmo@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Yuchung Cheng 提交于
RTT may be bogus with tall loss probe (TLP) when a packet is retransmitted and latter (s)acked without TCPCB_SACKED_RETRANS flag. For example, TLP calls __tcp_retransmit_skb() instead of tcp_retransmit_skb(). The skb timestamps are updated but the sacked flag is not marked with TCPCB_SACKED_RETRANS. As a result we'll get bogus RTT in tcp_clean_rtx_queue() or in tcp_sacktag_one() on spurious retransmission. The fix is to apply the sticky flag TCP_EVER_RETRANS to enforce Karn's check on RTT sampling. However this will disable F-RTO if timeout occurs after TLP, by resetting undo_marker in tcp_enter_loss(). We relax this check to only if any pending retransmists are still in-flight. Signed-off-by: NYuchung Cheng <ycheng@google.com> Acked-by: NEric Dumazet <edumazet@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Acked-by: NNandita Dukkipati <nanditad@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 27 2月, 2014 3 次提交
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由 Eric Dumazet 提交于
Upcoming congestion controls for TCP require usec resolution for RTT estimations. Millisecond resolution is simply not enough these days. FQ/pacing in DC environments also require this change for finer control and removal of bimodal behavior due to the current hack in tcp_update_pacing_rate() for 'small rtt' TCP_CONG_RTT_STAMP is no longer needed. As Julian Anastasov pointed out, we need to keep user compatibility : tcp_metrics used to export RTT and RTTVAR in msec resolution, so we added RTT_US and RTTVAR_US. An iproute2 patch is needed to use the new attributes if provided by the kernel. In this example ss command displays a srtt of 32 usecs (10Gbit link) lpk51:~# ./ss -i dst lpk52 Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port tcp ESTAB 0 1 10.246.11.51:42959 10.246.11.52:64614 cubic wscale:6,6 rto:201 rtt:0.032/0.001 ato:40 mss:1448 cwnd:10 send 3620.0Mbps pacing_rate 7240.0Mbps unacked:1 rcv_rtt:993 rcv_space:29559 Updated iproute2 ip command displays : lpk51:~# ./ip tcp_metrics | grep 10.246.11.52 10.246.11.52 age 561.914sec cwnd 10 rtt 274us rttvar 213us source 10.246.11.51 Old binary displays : lpk51:~# ip tcp_metrics | grep 10.246.11.52 10.246.11.52 age 561.914sec cwnd 10 rtt 250us rttvar 125us source 10.246.11.51 With help from Julian Anastasov, Stephen Hemminger and Yuchung Cheng Signed-off-by: NEric Dumazet <edumazet@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: Yuchung Cheng <ycheng@google.com> Cc: Larry Brakmo <brakmo@google.com> Cc: Julian Anastasov <ja@ssi.bg> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Florian Westphal 提交于
Three counters are added: - one to track when we went from non-zero to zero window - one to track the reverse - one counter incremented when we want to announce zero window, but can't because we would shrink current window. Suggested-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NFlorian Westphal <fw@strlen.de> Acked-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
While LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES can only be incremented in tcp_transmit_skb() from softirq (incoming message or timer activation), it is better to use NET_INC_STATS() instead of NET_INC_STATS_BH() as tcp_transmit_skb() can be called from process context. This will avoid copy/paste confusion when/if we want to add other SNMP counters in tcp_transmit_skb() Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Cc: Florian Westphal <fw@strlen.de> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 22 2月, 2014 1 次提交
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由 Eric Dumazet 提交于
This patch fixes two bugs in fastopen : 1) The tcp_sendmsg(..., @size) argument was ignored. Code was relying on user not fooling the kernel with iovec mismatches 2) When MTU is about 64KB, tcp_send_syn_data() attempts order-5 allocations, which are likely to fail when memory gets fragmented. Fixes: 783237e8 ("net-tcp: Fast Open client - sending SYN-data") Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: NYuchung Cheng <ycheng@google.com> Tested-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 20 2月, 2014 1 次提交
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由 Florian Westphal 提交于
Currently the kernel tries to announce a zero window when free_space is below the current receiver mss estimate. When a sender is transmitting small packets and reader consumes data slowly (or not at all), receiver might be unable to shrink the receive win because a) we cannot withdraw already-commited receive window, and, b) we have to round the current rwin up to a multiple of the wscale factor, else we would shrink the current window. This causes the receive buffer to fill up until the rmem limit is hit. When this happens, we start dropping packets. Moreover, tcp_clamp_window may continue to grow sk_rcvbuf towards rmem[2] even if socket is not being read from. As we cannot avoid the "current_win is rounded up to multiple of mss" issue [we would violate a) above] at least try to prevent the receive buf growth towards tcp_rmem[2] limit by attempting to move to zero-window announcement when free_space becomes less than 1/16 of the current allowed receive buffer maximum. If tcp_rmem[2] is large, this will increase our chances to get a zero-window announcement out in time. Reproducer: On server: $ nc -l -p 12345 <suspend it: CTRL-Z> Client: #!/usr/bin/env python import socket import time sock = socket.socket() sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) sock.connect(("192.168.4.1", 12345)); while True: sock.send('A' * 23) time.sleep(0.005) socket buffer on server-side will grow until tcp_rmem[2] is hit, at which point the client rexmits data until -EDTIMEOUT: tcp_data_queue invokes tcp_try_rmem_schedule which will call tcp_prune_queue which calls tcp_clamp_window(). And that function will grow sk->sk_rcvbuf up until it eventually hits tcp_rmem[2]. Thanks to Eric Dumazet for running regression tests. Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: NEric Dumazet <edumazet@google.com> Tested-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NFlorian Westphal <fw@strlen.de> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 14 2月, 2014 1 次提交
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由 stephen hemminger 提交于
One of my pet coding style peeves is the practice of adding extra return; at the end of function. Kill several instances of this in network code. I suppose some coccinelle wizardy could do this automatically. Signed-off-by: NStephen Hemminger <stephen@networkplumber.org> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 11 2月, 2014 1 次提交
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由 John Ogness 提交于
Commit 46d3ceab ("tcp: TCP Small Queues") introduced a possible regression for applications using TCP_NODELAY. If TCP session is throttled because of tsq, we should consult tp->nonagle when TX completion is done and allow us to send additional segment, especially if this segment is not a full MSS. Otherwise this segment is sent after an RTO. [edumazet] : Cooked the changelog, added another fix about testing sk_wmem_alloc twice because TX completion can happen right before setting TSQ_THROTTLED bit. This problem is particularly visible with recent auto corking, but might also be triggered with low tcp_limit_output_bytes values or NIC drivers delaying TX completion by hundred of usec, and very low rtt. Thomas Glanzmann for example reported an iscsi regression, caused by tcp auto corking making this bug quite visible. Fixes: 46d3ceab ("tcp: TCP Small Queues") Signed-off-by: NJohn Ogness <john.ogness@linutronix.de> Signed-off-by: NEric Dumazet <edumazet@google.com> Reported-by: NThomas Glanzmann <thomas@glanzmann.de> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 07 2月, 2014 1 次提交
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由 Eric Dumazet 提交于
TCP pacing depends on an accurate srtt estimation. Current srtt estimation is using jiffie resolution, and has an artificial offset of at least 1 ms, which can produce slowdowns when FQ/pacing is used, especially in DC world, where typical rtt is below 1 ms. We are planning a switch to usec resolution for linux-3.15, but in the meantime, this patch removes the 1 ms offset. All we need is to have tp->srtt minimal value of 1 to differentiate the case of srtt being initialized or not, not 8. The problematic behavior was observed on a 40Gbit testbed, where 32 concurrent netperf were reaching 12Gbps of aggregate speed, instead of line speed. This patch also has the effect of reporting more accurate srtt and send rates to iproute2 ss command as in : $ ss -i dst cca2 Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port tcp ESTAB 0 0 10.244.129.1:56984 10.244.129.2:12865 cubic wscale:6,6 rto:200 rtt:0.25/0.25 ato:40 mss:1448 cwnd:10 send 463.4Mbps rcv_rtt:1 rcv_space:29200 tcp ESTAB 0 390960 10.244.129.1:60247 10.244.129.2:50204 cubic wscale:6,6 rto:200 rtt:0.875/0.75 mss:1448 cwnd:73 ssthresh:51 send 966.4Mbps unacked:73 retrans:0/121 rcv_space:29200 Reported-by: NVytautas Valancius <valas@google.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 30 12月, 2013 1 次提交
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由 stephen hemminger 提交于
The following are only used in one file: tcp_connect_init tcp_set_rto Signed-off-by: NStephen Hemminger <stephen@networkplumber.org> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 18 12月, 2013 1 次提交
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由 Eric Dumazet 提交于
While investigating performance problems on small RPC workloads, I noticed linux TCP stack was always splitting the last TSO skb into two parts (skbs). One being a multiple of MSS, and a small one with the Push flag. This split is done even if TCP_NODELAY is set, or if no small packet is in flight. Example with request/response of 4K/4K IP A > B: . ack 68432 win 2783 <nop,nop,timestamp 6524593 6525001> IP A > B: . 65537:68433(2896) ack 69632 win 2783 <nop,nop,timestamp 6524593 6525001> IP A > B: P 68433:69633(1200) ack 69632 win 2783 <nop,nop,timestamp 6524593 6525001> IP B > A: . ack 68433 win 2768 <nop,nop,timestamp 6525001 6524593> IP B > A: . 69632:72528(2896) ack 69633 win 2768 <nop,nop,timestamp 6525001 6524593> IP B > A: P 72528:73728(1200) ack 69633 win 2768 <nop,nop,timestamp 6525001 6524593> IP A > B: . ack 72528 win 2783 <nop,nop,timestamp 6524593 6525001> IP A > B: . 69633:72529(2896) ack 73728 win 2783 <nop,nop,timestamp 6524593 6525001> IP A > B: P 72529:73729(1200) ack 73728 win 2783 <nop,nop,timestamp 6524593 6525001> We can avoid this split by including the Nagle tests at the right place. Note : If some NIC had trouble sending TSO packets with a partial last segment, we would have hit the problem in GRO/forwarding workload already. tcp_minshall_update() is moved to tcp_output.c and is updated as we might feed a TSO packet with a partial last segment. This patch tremendously improves performance, as the traffic now looks like : IP A > B: . ack 98304 win 2783 <nop,nop,timestamp 6834277 6834685> IP A > B: P 94209:98305(4096) ack 98304 win 2783 <nop,nop,timestamp 6834277 6834685> IP B > A: . ack 98305 win 2768 <nop,nop,timestamp 6834686 6834277> IP B > A: P 98304:102400(4096) ack 98305 win 2768 <nop,nop,timestamp 6834686 6834277> IP A > B: . ack 102400 win 2783 <nop,nop,timestamp 6834279 6834686> IP A > B: P 98305:102401(4096) ack 102400 win 2783 <nop,nop,timestamp 6834279 6834686> IP B > A: . ack 102401 win 2768 <nop,nop,timestamp 6834687 6834279> IP B > A: P 102400:106496(4096) ack 102401 win 2768 <nop,nop,timestamp 6834687 6834279> IP A > B: . ack 106496 win 2783 <nop,nop,timestamp 6834280 6834687> IP A > B: P 102401:106497(4096) ack 106496 win 2783 <nop,nop,timestamp 6834280 6834687> IP B > A: . ack 106497 win 2768 <nop,nop,timestamp 6834688 6834280> IP B > A: P 106496:110592(4096) ack 106497 win 2768 <nop,nop,timestamp 6834688 6834280> Before : lpq83:~# nstat >/dev/null;perf stat ./super_netperf 200 -t TCP_RR -H lpq84 -l 20 -- -r 4K,4K 280774 Performance counter stats for './super_netperf 200 -t TCP_RR -H lpq84 -l 20 -- -r 4K,4K': 205719.049006 task-clock # 9.278 CPUs utilized 8,449,968 context-switches # 0.041 M/sec 1,935,997 CPU-migrations # 0.009 M/sec 160,541 page-faults # 0.780 K/sec 548,478,722,290 cycles # 2.666 GHz [83.20%] 455,240,670,857 stalled-cycles-frontend # 83.00% frontend cycles idle [83.48%] 272,881,454,275 stalled-cycles-backend # 49.75% backend cycles idle [66.73%] 166,091,460,030 instructions # 0.30 insns per cycle # 2.74 stalled cycles per insn [83.39%] 29,150,229,399 branches # 141.699 M/sec [83.30%] 1,943,814,026 branch-misses # 6.67% of all branches [83.32%] 22.173517844 seconds time elapsed lpq83:~# nstat | egrep "IpOutRequests|IpExtOutOctets" IpOutRequests 16851063 0.0 IpExtOutOctets 23878580777 0.0 After patch : lpq83:~# nstat >/dev/null;perf stat ./super_netperf 200 -t TCP_RR -H lpq84 -l 20 -- -r 4K,4K 280877 Performance counter stats for './super_netperf 200 -t TCP_RR -H lpq84 -l 20 -- -r 4K,4K': 107496.071918 task-clock # 4.847 CPUs utilized 5,635,458 context-switches # 0.052 M/sec 1,374,707 CPU-migrations # 0.013 M/sec 160,920 page-faults # 0.001 M/sec 281,500,010,924 cycles # 2.619 GHz [83.28%] 228,865,069,307 stalled-cycles-frontend # 81.30% frontend cycles idle [83.38%] 142,462,742,658 stalled-cycles-backend # 50.61% backend cycles idle [66.81%] 95,227,712,566 instructions # 0.34 insns per cycle # 2.40 stalled cycles per insn [83.43%] 16,209,868,171 branches # 150.795 M/sec [83.20%] 874,252,952 branch-misses # 5.39% of all branches [83.37%] 22.175821286 seconds time elapsed lpq83:~# nstat | egrep "IpOutRequests|IpExtOutOctets" IpOutRequests 11239428 0.0 IpExtOutOctets 23595191035 0.0 Indeed, the occupancy of tx skbs (IpExtOutOctets/IpOutRequests) is higher : 2099 instead of 1417, thus helping GRO to be more efficient when using FQ packet scheduler. Many thanks to Neal for review and ideas. Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Nandita Dukkipati <nanditad@google.com> Cc: Van Jacobson <vanj@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Tested-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 11 12月, 2013 1 次提交
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由 stephen hemminger 提交于
Various spelling fixes in networking stack Signed-off-by: NStephen Hemminger <stephen@networkplumber.org> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 07 12月, 2013 1 次提交
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由 Eric Dumazet 提交于
Compiler doesn't know skb_shinfo(skb) pointer is usually constant. By using a temporary variable, we help generating smaller code. For example, tcp_init_nondata_skb() is inlined after this patch. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 20 11月, 2013 1 次提交
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由 Andrey Vagin 提交于
snd_nxt must be updated synchronously with sk_send_head. Otherwise tp->packets_out may be updated incorrectly, what may bring a kernel panic. Here is a kernel panic from my host. [ 103.043194] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048 [ 103.044025] IP: [<ffffffff815aaaaf>] tcp_rearm_rto+0xcf/0x150 ... [ 146.301158] Call Trace: [ 146.301158] [<ffffffff815ab7f0>] tcp_ack+0xcc0/0x12c0 Before this panic a tcp socket was restored. This socket had sent and unsent data in the write queue. Sent data was restored in repair mode, then the socket was switched from reapair mode and unsent data was restored. After that the socket was switched back into repair mode. In that moment we had a socket where write queue looks like this: snd_una snd_nxt write_seq |_________|________| | sk_send_head After a second switching from repair mode the state of socket was changed: snd_una snd_nxt, write_seq |_________ ________| | sk_send_head This state is inconsistent, because snd_nxt and sk_send_head are not synchronized. Bellow you can find a call trace, how packets_out can be incremented twice for one skb, if snd_nxt and sk_send_head are not synchronized. In this case packets_out will be always positive, even when sk_write_queue is empty. tcp_write_wakeup skb = tcp_send_head(sk); tcp_fragment if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) tcp_adjust_pcount(sk, skb, diff); tcp_event_new_data_sent tp->packets_out += tcp_skb_pcount(skb); I think update of snd_nxt isn't required, when a socket is switched from repair mode. Because it's initialized in tcp_connect_init. Then when a write queue is restored, snd_nxt is incremented in tcp_event_new_data_sent, so it's always is in consistent state. I have checked, that the bug is not reproduced with this patch and all tests about restoring tcp connections work fine. Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Cc: James Morris <jmorris@namei.org> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> Cc: Patrick McHardy <kaber@trash.net> Signed-off-by: NAndrey Vagin <avagin@openvz.org> Acked-by: NPavel Emelyanov <xemul@parallels.com> Acked-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 15 11月, 2013 1 次提交
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由 Eric Dumazet 提交于
After commit c9eeec26 ("tcp: TSQ can use a dynamic limit"), several users reported throughput regressions, notably on mvneta and wifi adapters. 802.11 AMPDU requires a fair amount of queueing to be effective. This patch partially reverts the change done in tcp_write_xmit() so that the minimal amount is sysctl_tcp_limit_output_bytes. It also remove the use of this sysctl while building skb stored in write queue, as TSO autosizing does the right thing anyway. Users with well behaving NICS and correct qdisc (like sch_fq), can then lower the default sysctl_tcp_limit_output_bytes value from 128KB to 8KB. This new usage of sysctl_tcp_limit_output_bytes permits each driver authors to check how their driver performs when/if the value is set to a minimum of 4KB. Normally, line rate for a single TCP flow should be possible, but some drivers rely on timers to perform TX completion and too long TX completion delays prevent reaching full throughput. Fixes: c9eeec26 ("tcp: TSQ can use a dynamic limit") Signed-off-by: NEric Dumazet <edumazet@google.com> Reported-by: NSujith Manoharan <sujith@msujith.org> Reported-by: NArnaud Ebalard <arno@natisbad.org> Tested-by: NSujith Manoharan <sujith@msujith.org> Cc: Felix Fietkau <nbd@openwrt.org> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 19 10月, 2013 1 次提交
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由 Neal Cardwell 提交于
Remove the specialized code in __tcp_retransmit_skb() that tries to trim any ACKed payload preceding a FIN before we retransmit (this was added in 1999 in v2.2.3pre3). This trimming code was made unreachable by the more general code added above it that uses tcp_trim_head() to trim any ACKed payload, with or without a FIN (this was added in "[NET]: Add segmentation offload support to TCP." in 2002 circa v2.5.33). Signed-off-by: NNeal Cardwell <ncardwell@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: NEric Dumazet <edumazet@google.com> Acked-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 18 10月, 2013 2 次提交
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由 Eric Dumazet 提交于
sk_can_gso() should only be used as a hint in tcp_sendmsg() to build GSO packets in the first place. (As a performance hint) Once we have GSO packets in write queue, we can not decide they are no longer GSO only because flow now uses a route which doesn't handle TSO/GSO. Core networking stack handles the case very well for us, all we need is keeping track of packet counts in MSS terms, regardless of segmentation done later (in GSO or hardware) Right now, if tcp_fragment() splits a GSO packet in two parts, @left and @right, and route changed through a non GSO device, both @left and @right have pcount set to 1, which is wrong, and leads to incorrect packet_count tracking. This problem was added in commit d5ac99a6 ("[TCP]: skb pcount with MTU discovery") Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Reported-by: NMaciej Żenczykowski <maze@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
TCP stack should make sure it owns skbs before mangling them. We had various crashes using bnx2x, and it turned out gso_size was cleared right before bnx2x driver was populating TC descriptor of the _previous_ packet send. TCP stack can sometime retransmit packets that are still in Qdisc. Of course we could make bnx2x driver more robust (using ACCESS_ONCE(shinfo->gso_size) for example), but the bug is TCP stack. We have identified two points where skb_unclone() was needed. This patch adds a WARN_ON_ONCE() to warn us if we missed another fix of this kind. Kudos to Neal for finding the root cause of this bug. Its visible using small MSS. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 12 10月, 2013 1 次提交
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由 Eric Dumazet 提交于
1) We need to take a timestamp only for skb that should be cloned. Other skbs are not in write queue and no rtt estimation is done on them. 2) the unlikely() hint is wrong for receivers (they send pure ACK) Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: MF Nowlan <fitz@cs.yale.edu> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-By: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 11 10月, 2013 1 次提交
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由 Eric Dumazet 提交于
In commit 634fb979 ("inet: includes a sock_common in request_sock") I forgot that the two ports in sock_common do not have same byte order : skc_dport is __be16 (network order), but skc_num is __u16 (host order) So sparse complains because ir_loc_port (mapped into skc_num) is considered as __u16 while it should be __be16 Let rename ir_loc_port to ireq->ir_num (analogy with inet->inet_num), and perform appropriate htons/ntohs conversions. Signed-off-by: NEric Dumazet <edumazet@google.com> Reported-by: NWu Fengguang <fengguang.wu@intel.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 10 10月, 2013 1 次提交
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由 Eric Dumazet 提交于
TCP listener refactoring, part 5 : We want to be able to insert request sockets (SYN_RECV) into main ehash table instead of the per listener hash table to allow RCU lookups and remove listener lock contention. This patch includes the needed struct sock_common in front of struct request_sock This means there is no more inet6_request_sock IPv6 specific structure. Following inet_request_sock fields were renamed as they became macros to reference fields from struct sock_common. Prefix ir_ was chosen to avoid name collisions. loc_port -> ir_loc_port loc_addr -> ir_loc_addr rmt_addr -> ir_rmt_addr rmt_port -> ir_rmt_port iif -> ir_iif Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 03 10月, 2013 1 次提交
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由 Andi Kleen 提交于
tcp_established_options assumes opts->options is 0 before calling, as it read modify writes it. For the tcp_current_mss() case the opts structure is not zeroed, so this can be done with uninitialized values. This is ok, because ->options is not read in this path. But it's still better to avoid the operation on the uninitialized field. This shuts up a static code analyzer, and presumably may help the optimizer. Cc: netdev@vger.kernel.org Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 01 10月, 2013 1 次提交
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由 Eric Dumazet 提交于
When TCP Small Queues was added, we used a sysctl to limit amount of packets queues on Qdisc/device queues for a given TCP flow. Problem is this limit is either too big for low rates, or too small for high rates. Now TCP stack has rate estimation in sk->sk_pacing_rate, and TSO auto sizing, it can better control number of packets in Qdisc/device queues. New limit is two packets or at least 1 to 2 ms worth of packets. Low rates flows benefit from this patch by having even smaller number of packets in queues, allowing for faster recovery, better RTT estimations. High rates flows benefit from this patch by allowing more than 2 packets in flight as we had reports this was a limiting factor to reach line rate. [ In particular if TX completion is delayed because of coalescing parameters ] Example for a single flow on 10Gbp link controlled by FQ/pacing 14 packets in flight instead of 2 $ tc -s -d qd qdisc fq 8001: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 1024 quantum 3028 initial_quantum 15140 Sent 1168459366606 bytes 771822841 pkt (dropped 0, overlimits 0 requeues 6822476) rate 9346Mbit 771713pps backlog 953820b 14p requeues 6822476 2047 flow, 2046 inactive, 1 throttled, delay 15673 ns 2372 gc, 0 highprio, 0 retrans, 9739249 throttled, 0 flows_plimit Note that sk_pacing_rate is currently set to twice the actual rate, but this might be refined in the future when a flow is in congestion avoidance. Additional change : skb->destructor should be set to tcp_wfree(). A future patch (for linux 3.13+) might remove tcp_limit_output_bytes Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Wei Liu <wei.liu2@citrix.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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